The text focuses on the current topic of research data. It presents results of qualitative research at Charles University in Prague. The aim of the research was to establish main characteristics of research data by content analysis of the sample of dissertations originated on Charles University in Prague. Research was motivated by the need of long-term preservation of this data and therefore uses primarily theoretical concepts and terminology from this area. Collected data (dissertation theses) were analysed by the methods of content analysis and grounded theory. Results of qualitative analysis are presented in this article.